1. Field of the Invention
The present disclosure relates to a scroll compressor and more particularly, to a bypass hole for bypassing a part of refrigerant compressed prior to discharge.
2. Description of the Related Art
The scroll compressor is a compressor forming a compression chamber made of a suction chamber, an intermediate pressure chamber, and a discharge chamber between both scrolls while performing a relative orbiting motion in engagement with a plurality of scrolls. Such a scroll compressor may obtain a relatively high compression ratio as compared with other types of compressors while smoothly connecting suction, compression, and discharge strokes of refrigerant, thereby obtaining stable torque. Therefore, the scroll compressor is widely used for compressing refrigerant in an air conditioner or the like. Recently, a high-efficiency scroll compressor having a lower eccentric load and an operation speed at 180 Hz or higher has been introduced.
The behavior characteristics of the scroll compressor may be determined by the shape of a fixed wrap and an orbiting wrap. The fixed wrap and the orbiting wrap may have any shape, but usually have a form of an involute curve that can be easily processed. The involute curve denotes a curve corresponding to a trajectory drawn by an end of thread when the, thread wound around a base circle having an arbitrary radius is released. When the involute curve used, a thickness of the wrap is constant and a capacity change rate may be also constant, and therefore, a number of turns of the wrap should be increased to obtain a high compression ratio, but in this case, it has a drawback in which a size of the compressor also increases.
Furthermore, the orbiting scroll is typically formed on one lateral surface of a circular disk-shaped end plate and the orbiting wrap, and a boss portion is formed on a rear surface that is not formed with the orbiting wrap and connected to a rotation shaft for orbitally driving the orbiting scroll. Such a shape may form an orbiting wrap over a substantially overall area of the end plate, thereby decreasing a diameter of the end plate portion for obtaining the same compression ratio. On the contrary, an action point to which a repulsive force of refrigerant is applied and an action point to which a reaction force for cancelling out the repulsive force is applied are separated from each other in a vertical direction, thereby causing a problem of increasing vibration or noise while the behavior of the orbiting scroll becomes unstable during the operation process.
In view of this, there is known a so-called axial through scroll compressor in which a point where the rotating shaft and the orbiting scroll are combined overlap with the orbiting wrap in a radial direction. In such an axial through scroll compressor, an action point of a repulsive force of refrigerant and an action point of the reaction force may act on the same point, thereby greatly reducing a problem of the inclination of the orbiting scroll.
On the other hand, according to the above-described axial through scroll compressor, a bypass hole may be formed in the middle of the compression chamber similarly to a typical scroll compressor to discharge a part of refrigerant to be compressed in advance. Through this, it may be possible to prevent over compression that may occur due to excessive inflow of liquid refrigerant and oil, in advance thereby enhancing compression efficiency as well as securing reliability.
However, in the above-described axial through scroll compressor in the related art, a discharge port may be formed at a position eccentric from the center of the orbiting scroll, thereby causing a difference in flow rate of refrigerant while compression gradients (volume reduction gradients) of both compression chambers become different from each other. In other words, as a compression chamber (hereinafter, referred to as a second compression chamber or a B pocket) having a shorter compression path length between both compression chambers may have a relatively steep compression gradient as compared to a compression chamber (hereinafter, referred to as a first compression chamber or a pocket) having a longer compression path length, a speed of refrigerant in the second compression chamber may become higher than the speed of refrigerant in the first compression chamber. Accordingly, over compression may occur in the second compression chamber as compared to the first compression chamber, thereby reducing the overall efficiency of the compressor.
However, according to a shaft-through scroll compressor in the related art, bypass holes belonging to both compression chambers may be formed to have the same cross sectional area at the same rotation angle position, and therefore, a difference in compression gradient with respect to both compression chambers cannot be solved. As a result, over-compression loss may occur in a compression chamber having a larger compression gradient (i.e., second compression chamber) as described above, thereby causing a problem of reducing the overall compression efficiency of the entire compressor.